119 research outputs found
Granular Flow Impact Forces on Protection Structures: MPM Numerical Simulations with Different Constitutive Models
No full textAbstractFlows of granular materials are among the most destructive of all landslide phenomena. The assessment of the potential damage caused by the granular flow and the design of protection structures require the knowledge of the landslide-structure interaction. Numerical simulations of these phenomena are very complex because large displacements, soil-structure interaction and complex non-linear soil behavior have to be considered. A key issue in the simulation of these phenomena is the definition of a constitutive model able to describe the granular material response under a wide range of strain rates. This study examines and compares the results obtained by different constitutive models, namely the elastic perfectly plastic model with Mohr-Coulomb failure criterion, and the viscoplastic model with Drucker-Prager yielding condition. To this aim, we consider a finite volume of granular material instantaneously released from the top of an inclined channel; the material flows downslope and bumps a rigid wall on which the forces are measured
Electrochemical Polymerization of Allylamine Copolymers
No full textWe describe for the first time the electro-oxidative synthesis and passivating properties of surface films of poly(allylamine) and copolymers of allylamine and diallylamine. Cyclic voltammetry and impedance spectra show that the films exhibit high charge-transfer resistance and that the addition of diallylamine causes improvements in the compactness and stability toward swelling of the films when compared to both allylamine and diallyamine, leading to coatings with high charge-transfer resistance up to 70 MΩ. We also show that removing oxygen before the polymerization further improves the films’ passivating properties
pH‐Responsive Motors and their Interaction with RAW 264.7 Macrophages
No full textAbstract Nano/micromotors are self‐propelled particles that use external stimuli to gain locomotion outperforming Brownian motion. Here, three different polymers are employed that are conjugated to silica particles through a pH‐labile linker. At slightly acidic pH, the linkers hydrolyze and release the polymeric chains, resulting in enhanced locomotion. The motors show a maximum velocity of ≈3 µm s−1 in cell media when poly(ethylene glycol) methyl ether methacrylate is asymmetrically distributed on the surface of the particles. Further, the motor internalization by RAW 264.7 macrophages was compared between motors, which have the polymer conjugated via a pH‐labile linker, and the irresponsive particles. Preliminary data indicate enhanced uptake, but further efforts are required to use responsive polymers to propel motors inside mammalian cells
Complexos de vanádio(IV) não oxo: estudo dos efeitos eletrônicos de grupos doadores e retiradores de elétrons
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas, Programa de Pós-Graduação em Química, Florianópolis, 2009.A existência de diferentes estados de oxidação é uma característica importante na química dos metais de transição. O potencial de oxirredução de um complexo metálico não depende somente da natureza do íon metálico. A presença de um ligante complexado ao metal altera a densidade eletrônica sobre os centros metálicos e a estabilidade dos mesmos, afetando os potenciais de oxirredução dos íons metálicos. Neste sentido, apresenta-se neste trabalho a síntese e caracterização de quatro novos ligantes H4btben-Br, H4btben-NO2, H4btben e H4btben-CH3, que diferem exclusivamente na presença dos grupos substituintes Br, NO2, H e CH3 nas posições para aos grupos fenolatos, e seus respectivos complexos de vanádio(IV) não-oxo, com o objetivo de estudar a variação no potencial redox do metal devido a presença desses substituintes. Os complexos foram caracterizados pelas técnicas de espectroscopia no infravermelho, UV-Vis e Ressonância Paramagnética Eletrônica (EPR). Os complexos [V(btben-NO2] e [V(btben)] também foram caracterizados através de suas estruturas cristalinas por difração de raios X. Para estudar a influência no potencial redox do íon metálico pelos quatro grupos substituintes Br, NO2, H e CH3, foram realizados estudos eletroquímicos dos complexos através do método de voltametria cíclica a diferentes velocidades de varredura e seus potenciais correlacionados com os parâmetros de Hammett dos respectivos substituintes, onde se observou uma correlação linear, demonstrando uma influência direta dos grupos nos potenciais redox desses complexos
Dino Buzzati Interpreter of Silvio Ceccato: Il grande ritratto and Its Debt to Cybernetics
No full textThis essay examines the impact of the studies conducted by cybernetician Silvio Ceccato on Buzzati’s novella Il grande ritratto (1959). While the link connecting Buzzati’s fictional rendition of an artificial intelligence (AI) in the novella and Ceccato’s theories have previously been established by the critics, this study explores in-depth and for the first time how truly knowledgeable and receptive the author was to the then new field of cybernetics. By cross-referencing Il grande ritratto against Ceccato’s work, and Buzzati’s own newspaper articles dedicated to it, this study demonstrates how the novella’s techno-scientific substratum is fundamental to understand why Buzzati chose to write the character of Numero Uno, the AI, the way he did. Indeed, the story departs from the traditional depiction of humanoid robots and anticipates some of the contemporary issues concerning AI, from the “black box problem” and autonomy in neural networks, to biases in data. The purpose of this essay is to situate Il grande ritratto within Buzzati’s well-informed curiosity for Ceccato’s theories, while also showing how the author’s engagement with cybernetics was not at all atypical, but rather in line with the enthusiastic interest for the field animating many Italian artists between the late 1950s and early 1960s
Dino Buzzati Interpreter of Silvio Ceccato: Il grande ritratto and Its Debt to Cybernetics
No full textThis essay examines the impact of the studies conducted by cybernetician Silvio Ceccato on Buzzati’s novella Il grande ritratto (1959). While the link connecting Buzzati’s fictional rendition of an artificial intelligence (AI) in the novella and Ceccato’s theories have previously been established by the critics, this study explores in-depth and for the first time how truly knowledgeable and receptive the author was to the then new field of cybernetics. By cross-referencing Il grande ritratto against Ceccato’s work, and Buzzati’s own newspaper articles dedicated to it, this study demonstrates how the novella’s techno-scientific substratum is fundamental to understand why Buzzati chose to write the character of Numero Uno, the AI, the way he did. Indeed, the story departs from the traditional depiction of humanoid robots and anticipates some of the contemporary issues concerning AI, from the “black box problem” and autonomy in neural networks, to biases in data. The purpose of this essay is to situate Il grande ritratto within Buzzati’s well-informed curiosity for Ceccato’s theories, while also showing how the author’s engagement with cybernetics was not at all atypical, but rather in line with the enthusiastic interest for the field animating many Italian artists between the late 1950s and early 1960s
Applying and combining three different aspect mining techniques
No full textUnderstanding a software system at source-code level requires understanding the different concerns that it addresses, which in turn requires a way to identify these concerns in the source code. Whereas some concerns are explicitly represented by program entities (like classes, methods and variables) and thus are easy to identify, crosscutting concerns are not captured by a single program entity but are scattered over many program entities and are tangled with the other concerns. Because of their crosscutting nature, such crosscutting concerns are difficult to identify, and reduce the understandability of the system as a whole. In this paper, we report on a combined experiment in which we try to identify crosscutting concerns in the JHotDraw framework automatically. We first apply three independently developed aspect mining techniques to JHotDraw and evaluate and compare their results. Based on this analysis, we present three interesting combinations of these three techniques, and show how these combinations provide a more complete coverage of the detected concerns as compared to the original techniques individually. Our results are a first step towards improving the understandability of a system that contains crosscutting concerns, and can be used as a basis for refactoring the identified crosscutting concerns into aspects.Software TechnologyElectrical Engineering, Mathematics and Computer Scienc
The Architect as Toolmaker: Computer-Based Generative Design Tools and Methods
No full textThe purpose of this paper is to illustrate the results of various stages of research into the development of generative design methods and tools, conducted at the Architectural Association School of Architecture (London), Imperial College of Science, Technology and Medicine (London), and independently. A brief introduction explains the philosophy behind generative design methods and their basic principles. A number of computer software tools and projects developed by the author are then used to illustrate the methodology, techniques and features of generative design and its organisation of information
- …
